Diversification of T cell responses to carboxy-terminal determinants within the 65-kD heat-shock protein is involved in regulation of autoimmune arthritis

The Utility of Peptide Ligand-Functionalized Liposomes for Subcutaneous Drug Delivery for Arthritis Therapy

Liposomes and other types of nanoparticles are increasingly being explored for drug delivery in a variety of diseases. There is an impetus in the field to exploit different types of ligands to functionalize nanoparticles to guide them to the diseased site. Most of this work has been conducted in the cancer field, with relatively much less information from autoimmune diseases, such as rheumatoid arthritis (RA). Furthermore, in RA, many drugs are self-administered by patients subcutaneously (SC). In this context, we have examined the attributes of liposomes functionalized with a novel joint-homing peptide (denoted ART-1) for arthritis therapy using the SC route. This peptide was previously identified following phage peptide library screening in the rat adjuvant arthritis (AA) model. Our results show a distinct effect of this peptide ligand on increasing the zeta potential of liposomes. Furthermore, liposomes injected SC into arthritic rats showed preferential homing to arthritic joints, following a migration profile in vivo similar to that of intravenously injected liposomes, except for a less steep decline after the peak. Finally, liposomal dexamethasone administered SC was more effective than the unpackaged (free) drug in suppressing arthritis progression in rats. We suggest that with suitable modifications, this SC liposomal treatment modality can be adapted for human RA therapy.

Molecular Actors of Inflammation and Their Signaling Pathways: Mechanistic Insights from Zebrafish

Inflammation is a hallmark of the physiological response to aggressions. It is orchestrated by a plethora of molecules that detect the danger, signal intracellularly, and activate immune mechanisms to fight the threat. Understanding these processes at a level that allows to modulate their fate in a pathological context strongly relies on in vivo studies, as these can capture the complexity of the whole process and integrate the intricate interplay between the cellular and molecular actors of inflammation. Over the years, zebrafish has proven to be a well-recognized model to study immune responses linked to human physiopathology. We here provide a systematic review of the molecular effectors of inflammation known in this vertebrate and recapitulate their modes of action, as inferred from sterile or infection-based inflammatory models. We present a comprehensive analysis of their sequence, expression, and tissue distribution and summarize the tools that have been developed to study their function. We further highlight how these tools helped gain insights into the mechanisms of immune cell activation, induction, or resolution of inflammation, by uncovering downstream receptors and signaling pathways. These progresses pave the way for more refined models of inflammation, mimicking human diseases and enabling drug development using zebrafish models.

The Anti-Inflammatory and Immunomodulatory Activities of Natural Products to Control Autoimmune Inflammation

Inflammation is an integral part of autoimmune diseases, which are caused by dysregulation of the immune system. This dysregulation involves an imbalance between pro-inflammatory versus anti-inflammatory mediators. These mediators include various cytokines and chemokines; defined subsets of T helper/T regulatory cells, M1/M2 macrophages, activating/tolerogenic dendritic cells, and antibody-producing/regulatory B cells. Despite the availability of many anti-inflammatory/immunomodulatory drugs, the severe adverse reactions associated with their long-term use and often their high costs are impediments in effectively controlling the disease process. Accordingly, suitable alternatives are being sought for these conventional drugs. Natural products offer promising adjuncts/alternatives in this regard. The availability of specific compounds isolated from dietary/medicinal plant extracts have permitted rigorous studies on their disease-modulating activities and the mechanisms involved therein. Here, we describe the basic characteristics, mechanisms of action, and preventive/therapeutic applications of 5 well-characterized natural product compounds (Resveratrol, Curcumin, Boswellic acids, Epigallocatechin-3-gallate, and Triptolide). These compounds have been tested extensively in animal models of autoimmunity as well as in limited clinical trials in patients having the corresponding diseases. We have focused our description on predominantly T cell-mediated diseases, such as rheumatoid arthritis, multiple sclerosis, Type 1 diabetes, ulcerative colitis, and psoriasis.

Danggui Niantong granules ameliorate rheumatoid arthritis by regulating intestinal flora and promoting mitochondrial apoptosis

CONTEXT

Danggui Niantong Granules (DGNTG) are a valid and reliable traditional herbal formula, commonly used in clinical practice to treat rheumatoid arthritis (RA). However, the mechanism of its effect on RA remains unclear.

OBJECTIVE

An investigation of the therapeutic effects of DGNTG on RA.

MATERIALS AND METHODS

Twenty-four male Sprague-Dawley (SD) rats were divided into four groups: control, model, DGNTG (2.16 g/kg, gavage), methotrexate (MTX) (1.35 mg/kg, gavage) for 28 days. The morphology of synovial and ankle tissues was observed by haematoxylin-eosin staining. The responses of mitochondrial apoptosis were assessed by qPCR, Western blotting and immunohistochemical staining. Rat faeces were analysed by 16S rRNA sequencing.

RESULTS

Our results showed that DGNTG treatment reduced AI scores (7.83 ± 0.37 vs. 4.67 ± 0.47, p < 0.01) and paw volumes (7.63 ± 0.17 vs. 6.13 ± 0.11, p < 0.01) compared with the model group. DGNTG also increased the expression of Bax (0.34 ± 0.03 vs. 0.73 ± 0.03, p < 0.01), cytochrome c (CYTC) (0.24 ± 0.02 vs. 0.64 ± 0.01, p < 0.01) and cleaved caspase-9 (0.24 ± 0.04 vs. 0.83 ± 0.08, p < 0.01), and decreased bcl-2 (1.70 ± 0.11 vs. 0.60 ± 0.09, p < 0.01) expression. DGNTG treatment regulated the structure of gut microbiota.

DISCUSSION AND CONCLUSIONS

DGNTG ameliorated RA by promoting mitochondrial apoptosis, which may be associated with regulating gut microbiota structure. DGNTG can be used as a supplement and alternative drug for the treatment of RA; its ability to prevent RA deserves further study.

Viewing Autoimmune Pathogenesis from the Perspective of Antigen Processing and Determinant Hierarchy

Autoimmunity results from the breakdown of immune tolerance to defined target self antigens. Like any foreign antigen, a self antigen is continuously processed by antigen-presenting cells (APCs) and its epitopes are displayed by the major histocompatibility complex on the cell surface (dominant epitopes). However, this self antigen fails to induce a T cell response as the T cells against its dominant epitopes have been purged in the thymus during negative selection. In contrast, the T cells against poorly processed (cryptic) self epitopes escape tolerance induction in the thymus and make it to the periphery. Such T cells are generally harmless as their cognate epitopes in the periphery are not presented efficiently. But, under conditions of inflammation and immune activation, previously cryptic epitopes can be revealed on the APC surface for activation of ambient T cells. This can initiate autoimmunity in individuals who are susceptible owing to their genetic and environmental constellation. Subsequent waves of enhanced processing of other epitopes on the same or different self antigens then cause "diversification" or "spreading" of the initial T cell response, resulting in propagation of autoimmunity. However, depending on the disease process and the self antigen involved, "epitope spreading" may instead contribute to natural regression of autoimmunity. This landmark conceptual framework developed by Eli Sercarz and his team ties together determinant hierarchy, selection of epitope-specific T cells, and the induction/progression of autoimmunity. I am extremely fortunate to have worked with Eli and to have been a part of this fascinating research endeavor.

Remnant Epitopes Generating Autoimmunity: From Model to Useful Paradigm

Autoimmune diseases are defined as pathologies of adaptive immunity by the presence of autoantibodies or MHC-restricted autoantigen-reactive T cells. Because autoreactivity is a normal process based on mechanisms producing repertoires of antibodies and T cell receptors, crucial questions about disease mechanisms and key steps for interference have been outstanding. We defined 25 years ago the 'remnant epitopes generate autoimmunity' (REGA)-model in which extracellular proteases from innate immune cells generate autoantigens. Here, we refine the REGA-model, tested in diseases ranging from organ-specific autoimmune diseases to systemic lupus erythematosus. It now constitutes a paradigm in which remnant epitopes generate, maintain, and regulate autoimmunity; are dependent on genetic and epigenetic influences; are produced in a disease phase-specific manner; and have therapeutic implications when targeted.

Peptide-Based Vaccination Therapy for Rheumatic Diseases

Rheumatic diseases are extremely heterogeneous diseases with substantial risks of morbidity and mortality, and there is a pressing need in developing more safe and cost-effective treatment strategies. Peptide-based vaccination is a highly desirable strategy in treating noninfection diseases, such as cancer and autoimmune diseases, and has gained increasing attentions. This review is aimed at providing a brief overview of the recent advances in peptide-based vaccination therapy for rheumatic diseases. Tremendous efforts have been made to develop effective peptide-based vaccinations against rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), while studies in other rheumatic diseases are still limited. Peptide-based active vaccination against pathogenic cytokines such as TNF-α and interferon-α (IFN-α) is shown to be promising in treating RA or SLE. Moreover, peptide-based tolerogenic vaccinations also have encouraging results in treating RA or SLE. However, most studies available now have been mainly based on animal models, while evidence from clinical studies is still lacking. The translation of these advances from experimental studies into clinical therapy remains impeded by some obstacles such as species difference in immunity, disease heterogeneity, and lack of safe delivery carriers or adjuvants. Nevertheless, advances in high-throughput technology, bioinformatics, and nanotechnology may help overcome these impediments and facilitate the successful development of peptide-based vaccination therapy for rheumatic diseases.

Common innate pathways to autoimmune disease

Until recently, autoimmune disease research has primarily been focused on elucidating the role of the adaptive immune system. In the past decade or so, the role of the innate immune system in the pathogenesis of autoimmunity has increasingly been realized. Recent findings have elucidated paradigm-shifting concepts, for example, the implications of "trained immunity" and a dysbiotic microbiome in the susceptibility of predisposed individuals to clinical autoimmunity. In addition, the application of modern technologies such as the quantum dot (Qdot) system and 'Omics' (e.g., genomics, proteomics, and metabolomics) data-processing tools has proven fruitful in revisiting mechanisms underlying autoimmune pathogenesis and in identifying novel therapeutic targets. This review highlights recent findings discussed at the American Autoimmune Related Disease Association (AARDA) 2019 colloquium. The findings covering autoimmune diseases and autoinflammatory diseases illustrate how new developments in common innate immune pathways can contribute to the better understanding and management of these immune-mediated disorders.

Peptide-targeted liposomal delivery of dexamethasone for arthritis therapy

Aim: Rheumatoid arthritis is an autoimmune disease affecting the joints. Antiarthritic drugs are given systemically, thereby exposing various healthy organs to these drugs, resulting in adverse reactions. Accordingly, there is an urgent need for targeted drug delivery methods for inflamed joints. Materials & methods: We developed a liposomal drug delivery system using a novel peptide ligand (CKPFDRALC) named ART-2, which homes to the inflamed joints when injected intravenously to rats with adjuvant-induced arthritis. Results: The ART-2-coated liposomes encapsulating an antiarthritic drug, dexamethasone (DEX), were more effective in inhibiting arthritis progression than control-DEX liposomes or free DEX, despite a comparable safety profile. Conclusion: Peptide-targeted therapy has advantages over conventional drug delivery and can be adapted for rheumatoid arthritis therapy.

Modulation of autoimmune arthritis by environmental 'hygiene' and commensal microbiota

Observations in patients with autoimmune diseases and studies in animal models of autoimmunity have revealed that external environmental factors including exposure to microbes and the state of the host gut microbiota can influence susceptibility to autoimmunity and subsequent disease development. Mechanisms underlying these outcomes continue to be elucidated. These include deviation of the cytokine response and imbalance between pathogenic versus regulatory T cell subsets. Furthermore, specific commensal organisms are associated with enhanced severity of arthritis in susceptible individuals, while exposure to certain microbes or helminths can afford protection against this disease. In addition, the role of metabolites (e.g., short-chain fatty acids, tryptophan catabolites), produced either by the microbes themselves or from their action on dietary products, in modulation of arthritis is increasingly being realized. In this context, re-setting of the microbial dysbiosis in RA using prebiotics, probiotics, or fecal microbial transplant is emerging as a promising approach for the prevention and treatment of arthritis. It is hoped that advances in defining the interplay between gut microbiota, dietary products, and bioactive metabolites would help in the development of therapeutic regimen customized for the needs of individual patients in the near future.

The Micro-RNA Expression Profiles of Autoimmune Arthritis Reveal Novel Biomarkers of the Disease and Therapeutic Response

Rheumatoid arthritis (RA) is a chronic autoimmune disease of the joints affecting about 0.3–1% of the population in different countries. About 50–60 percent of RA patients respond to presently used drugs. Moreover, the current biomarkers for RA have inherent limitations. Consequently, there is a need for additional, new biomarkers for monitoring disease activity and responsiveness to therapy of RA patients. We examined the micro-RNA (miRNA) profile of immune (lymphoid) cells of arthritic Lewis rats and arthritic rats treated with celastrol, a natural triterpenoid. Experimental and bioinformatics analyses revealed 8 miRNAs (miR-22, miR-27a, miR-96, miR-142, miR-223, miR-296, miR-298, and miR-451) and their target genes in functional pathways important for RA pathogenesis. Interestingly, 6 of them (miR-22, miR-27a, miR-96, miR-142, miR-223, and miR-296) were further modulated by celastrol treatment. Interestingly, serum levels of miR-142, miR-155, and miR-223 were higher in arthritic versus control rats, whereas miR-212 showed increased expression in celastrol-treated rats compared with arthritic rats or control rats. This is the first study on comprehensive miRNA expression profiling in the adjuvant-induced arthritis (AA) model and it also has revealed new miRNA targets for celastrol in arthritis. We suggest that subsets of the above miRNAs may serve as novel biomarkers of disease activity and therapeutic response in arthritis.

Peptide-directed liposomal delivery improves the therapeutic index of an immunomodulatory cytokine in controlling autoimmune arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the synovial tissue of the joints. Inadequately controlled disease may cause severe joint damage and deformity. Currently, the anti-arthritic drugs are given systemically, and therefore, they are widely distributed to other organs that are not the intended therapeutic targets. Accordingly, using a particular dose/regimen of a drug to achieve an effective local concentration of the drug in arthritic joints may lead to expected adverse effects involving other organs. Thus, improved methods of drug delivery are needed for arthritis therapy. One attractive approach is the targeting of a systemically administered drug to the inflamed joints. We describe here a prototypic drug delivery system using a novel peptide ligand denoted as ART-1. We previously reported ART-1 (=ADK) as a peptide that preferentially homes to the inflamed joints of arthritic rats and binds to synovial endothelial cells. We tested the ART-1-coated liposomes encapsulating a fluorescent compound for binding to activated endothelial cells in vitro and homing to arthritic joints in vivo, compared to control liposomes lacking the ART-1 coating. Similar liposomes but encapsulating an immunomodulatory cytokine interleukin-27 (ART-1-IL-27 liposomes) were tested for their anti-arthritic activity compared with control liposomes. ART-1-displaying liposomes showed better binding to endothelial cells as well as in vivo homing to arthritic joints compared to control liposomes. Furthermore, ART-1-IL-27 liposomes, when intravenously injected to arthritic rats after the onset of arthritis, were more effective in suppressing disease progression than control-IL-27 liposomes lacking ART-1 or free IL-27 at an equivalent dose of IL-27. In addition, ART-1-directed liposomal IL-27 had a better safety profile than undirected liposomal IL-27 or free IL-27, thereby offering an improved therapeutic index for IL-27 therapy. These results provide a proof-of concept for the use of a novel joint-homing peptide for targeted delivery of drugs including biologics or small molecule compounds to arthritic joints with enhanced efficacy and reduced systemic exposure. This targeted therapy platform may be suitable for use in RA patients.

Mycobacterium avium subspecies paratuberculosis - an important food borne pathogen of high public health significance with special reference to India: an update

This review underlines the public health significance of 'Indian Bison Type' of Mycobacterium avium subspecies paratuberculosis (MAP) and also its potential as 'zoonotic infection'. In the absence of control programs, bio-load of MAP is increasing and if we take total population of animals (500 million plus) and human beings (1.23 billion plus) into account, the number of infected animals and human beings will run into millions in India. Our research on screening of over 26,000 domestic livestock for MAP infection using 4 different diagnostic tests (microscopy, culture, ELISA and PCR), during last 31 years has shown that the average bio-load of MAP in the livestock population of India is very high (cattle 43%, buffaloes 36%, goats 23% and sheep 41%). 'Mass screening' of 28,291 human samples between 2008-2016 revealed also high bio-load of MAP. It has been proved that MAP is not in-activated during pasteurization and therefore live bacilli are continuously reaching human population by consumption of even pasteurized milk and other milk products. Live bacilli have also been recovered from meat products and the environment thus illustrating the potential of MAP as pathogen of public health concern. However, at present, there is inadequate scientific evidence to confirm a conclusive link between MAP infection and Johne's disease in ruminants and some cases of Crohn's disease in human beings.

Immunomodulation of autoimmune arthritis by pro-inflammatory cytokines

Pro-inflammatory cytokines promote autoimmune inflammation and tissue damage, while anti-inflammatory cytokines help resolve inflammation and facilitate tissue repair. Over the past few decades, this general feature of cytokine-mediated events has offered a broad framework to comprehend the pathogenesis of autoimmune and other immune-mediated diseases, and to successfully develop therapeutic approaches for diseases such as rheumatoid arthritis (RA). Anti-tumor necrosis factor-α (TNF-α) therapy is a testimony in support of this endeavor. However, many patients with RA fail to respond to this or other biologics, and some patients may suffer unexpected aggravation of arthritic inflammation or other autoimmune effects. These observations combined with rapid advancements in immunology in regard to newer cytokines and T cell subsets have enforced a re-evaluation of the perceived pathogenic attribute of the pro-inflammatory cytokines. Studies conducted by others and us in experimental models of arthritis involving direct administration of IFN-γ or TNF-α; in vivo neutralization of the cytokine; the use of animals deficient in the cytokine or its receptor; and the impact of the cytokine or anti-cytokine therapy on defined T cell subsets have revealed paradoxical anti-inflammatory and immunoregulatory attributes of these two cytokines. Similar studies in other models of autoimmunity as well as limited studies in arthritis patients have also unveiled the disease-protective effects of these pro-inflammatory cytokines. A major mechanism in this regard is the altered balance between the pathogenic T helper 17 (Th17) and protective T regulatory (Treg) cells in favor of the latter. However, it is essential to consider that this aspect of the pro-inflammatory cytokines is context-dependent such that the dose and timing of intervention, the experimental model of the disease under study, and the differences in individual responsiveness can influence the final outcomes. Nevertheless, the realization that pro-inflammatory cytokines can also be immunoregulatory offers a new perspective in fully understanding the pathogenesis of autoimmune diseases and in designing better therapies for controlling them.

Heat shock proteins and their immunomodulatory role in inflammatory arthritis

Autoimmune diseases, including inflammatory arthritis, are characterized by a loss of self-tolerance, leading to an excessive immune responses and subsequent ongoing inflammation. Current therapies are focused on dampening this inflammation, but a permanent state of tolerance is seldom achieved. Therefore, novel therapies that restore and maintain tolerance are needed. Tregs could be a potential target to achieve permanent immunotolerance. Activation of Tregs can be accomplished when they recognize and bind their specific antigens. HSPs are proteins present in all cells and are upregulated during inflammation. These proteins are immunogenic and can be recognized by Tregs. Several studies in animal models and in human clinical trials have shown the immunoregulatory effects of HSPs and their protective effects in inflammatory arthritis. In this review, an overview is presented of the immunomodulatory effects of several members of the HSP family in general and in inflammatory arthritis. These effects can be attributed to the activation of Tregs through cellular interactions within the immune system. The effect of HSP-specific therapies in patients with inflammatory arthritis should be explored further, especially with regard to long-term efficacy and safety and their use in combination with current therapeutic approaches.

Modulation of Adjuvant Arthritis by Cellular and Humoral Immunity to Hsp65

Heat shock proteins (Hsps) are highly conserved, and their expression is upregulated in cells by heat and other stressful stimuli. These proteins play a vital role in preserving the structural and functional integrity of cells under stress. Despite the ubiquitous expression of Hsps in an individual, the immune system is not fully tolerant to them. In fact, Hsps are highly immunogenic in nature, and immune response to these proteins is observed in various inflammatory and autoimmune diseases. Studies on the immunopathogenesis of autoimmune arthritis in the rat adjuvant arthritis (AA) model of human rheumatoid arthritis (RA) as well as observations in patients with RA and juvenile idiopathic arthritis (JIA) have unraveled immunoregulatory attributes of self-Hsp65-directed immunity. Notable features of Hsp65 immunity in AA include protection rather than disease induction following immunization of Lewis rats with self (rat)-Hsp65; the diversification of T cell response to mycobacterial Hsp65 during the course of AA and its association with spontaneous induction of response to self-Hsp65; the cross-reactive T cells recognizing foreign and self homologs of Hsp65 and their role in disease suppression in rats; the suppressive effect of antibodies to Hsp65 in AA; and the use of Hsp65, its peptides, or altered peptide ligands in controlling autoimmune pathology. The results of studies in the AA model have relevance to RA and JIA. We believe that these insights into Hsp65 immunity would not only advance our understanding of the disease process in RA/JIA, but also lead to the development of novel therapeutic approaches for autoimmune arthritis.

Extracellular HSPs: The Complicated Roles of Extracellular HSPs in Immunity

Extracellular heat-shock proteins (HSPs) interact with the immune system in a very complex manner. Many such HSPs exert powerful effects on the immune response, playing both stimulatory and regulatory roles. However, the influence of the HSPs on immunity appears to be positive or negative in nature – rarely neutral. Thus, the HSPs can act as dominant antigens and can comprise key components of antitumor vaccines. They can also function as powerful immunoregulatory agents and, as such, are employed to treat inflammatory diseases or to extend the lifespan of tissue transplants. Small modifications in the cellular milieu have been shown to flip the allegiances of HSPs from immunoregulatory agents toward a potent inflammatory alignment. These mutable properties of HSPs may be related to the ability of these proteins to interact with multiple receptors often with mutually confounding properties in immune cells. Therefore, understanding the complex immune properties of HSPs may help us to harness their potential in treatment of a range of conditions.

Tinospora cordifolia inhibits autoimmune arthritis by regulating key immune mediators of inflammation and bone damage

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints leading to tissue damage. Despite the availability of potent drugs including the biologics, many patients fail to respond to them, whereas others suffer adverse effects following long-term use of these drugs. Accordingly, the use of natural herbal products by RA patients has been increasing over the years. However, limited information about the mechanism of action of these natural products is a major shortcoming that prevents the widespread acceptance of herbal therapy by professionals and patients alike. In this study, we demonstrated the anti-arthritic activity of Tinospora cordifolia extract (TCE) using the rat adjuvant-induced arthritis model of human RA and elaborated the immune mechanisms underlying this effect. TCE treatment suppressed arthritic inflammation and bone and cartilage damage. The anti-inflammatory effect of TCE was mediated via reduction of the pro-inflammatory cytokines such as: IL-1β, TNF-α, IL-6, and IL-17; the frequency of IL-17-producing T cells; and the production of chemokines such as RANTES. Furthermore, TCE treatment limited bone damage by shifting the balance of mediators of bone remodeling (e.g., receptor activator of nuclear factor-kB ligand [RANKL] and MMP-9) in favor of anti-osteoclastic activity. Our results suggest that TCE and its bioactive components should be evaluated for their utility as therapeutic adjuncts to conventional drugs against RA.

Mycobacterium avium ss. paratuberculosis Zoonosis - The Hundred Year War - Beyond Crohn's Disease

The factitive role of Mycobacterium avium ss. paratuberculosis (MAP) in Crohn's disease has been debated for more than a century. The controversy is due to the fact that Crohn's disease is so similar to a disease of MAP-infected ruminant animals, Johne's disease; and, though MAP can be readily detected in the infected ruminants, it is much more difficult to detect in humans. Molecular techniques that can detect MAP in pathologic Crohn's specimens as well as dedicated specialty labs successful in culturing MAP from Crohn's patients have provided strong argument for MAP's role in Crohn's disease. Perhaps more incriminating for MAP as a zoonotic agent is the increasing number of diseases with which MAP has been related: Blau syndrome, type 1 diabetes, Hashimoto thyroiditis, and multiple sclerosis. In this article, we debate about genetic susceptibility to mycobacterial infection and human exposure to MAP; moreover, it suggests that molecular mimicry between protein epitopes of MAP and human proteins is a likely bridge between infection and these autoimmune disorders.

Temporal cytokine expression and the target organ attributes unravel novel aspects of autoimmune arthritis

Susceptibility to autoimmunity is determined by multiple factors. Defining the contribution of the quantitative versus qualitative aspects of antigen-directed immune responses as well as the factors influencing target organ susceptibility is vital to advancing the understanding of the pathogenesis of autoimmunity. In a series of studies, we have addressed these issues using the adjuvant-induced arthritis (AA) model of human rheumatoid arthritis (RA). Lewis rats are susceptible to AA following immunization with heat-killed Mycobacterium tuberculosis H37Ra, whereas Wistar-Kyoto (WKY) rats of the same MHC (major histocompatibility complex) haplotype are resistant. Comparative studies on these and other susceptible/resistant rodent strains have offered interesting insights into differential cytokine responses in the face of comparable T cell proliferative response to the disease relevant antigens. Study of the cytokine kinetics have also permitted validation of the disease-protective versus disease-aggravating effects of specific cytokines by treatment of rats/mice with those cytokines at different phases of the disease. In regard to the target organ attributes, the migration of arthritogenic leukocytes into the joints; the expression of mediators of inflammation, angiogenesis, and tissue damage; the role of vascular permeability; and the characteristics of vascular endothelial cells have been examined. Further, various inhibitors of angiogenesis are effective in suppressing arthritis. Taken together, the differential cytokine responses and unique attributes of the target organ have revealed novel aspects of disease susceptibility and joint damage in AA. The translation of this basic research in animal models to RA patients would not only advance our understanding of the disease process, but also offer novel avenues for immunomodulation of this disease.

Kinetics and interplay of mediators of inflammation-induced bone damage in the course of adjuvant arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation, bone erosion, and cartilage destruction in the joints. It is increasingly being realized that inflammation might play an important role in inducing bone damage in arthritis. However, there is limited validation of this concept in vivo in well-controlled experimental conditions. We addressed this issue using the adjuvant arthritis (AA) model of RA. In AA, the draining lymph nodes are the main sites of activation of pathogenic leukocytes, which then migrate into the joints leading to the induction of arthritis. We tested the temporal kinetics of mediators of bone damage [e.g., receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG) and osteopontin (OPN)] and inflammation (pro-inflammatory cytokines and chemokines) in the draining lymph node cells (LNC) at different phases of AA, and then examined their inter-relationships. Our study revealed that, together with cytokines/chemokines, some of the mediators of bone remodeling are also produced in LNC. Various cytokines/chemokines showed distinct kinetics of expression as well as patterns of correlation with mediators of bone remodeling at different phases of the disease. Pro-inflammatory cytokines such as TNF-alpha are known to play an important role in bone damage. Interestingly, there was a positive correlation between TNF-alpha and RANKL, between RANKL and each of the 3 chemokines tested (RANTES, MIP-1alpha, and GRO/KC), and between TNF-alpha and RANTES. Our results in the AA model lend support to the concept of osteo-immune crosstalk during the course of autoimmune arthritis.

Comparative antigen-induced gene expression profiles unveil novel aspects of susceptibility/resistance to adjuvant arthritis in rats

Lewis (LEW) and Wistar Kyoto (WKY) rats of the same major histocompatibility complex (MHC) haplotype (RT.1(l)) display differential susceptibility to adjuvant-induced arthritis (AIA). LEW are susceptible while WKY are resistant to AIA. To gain insights into the mechanistic basis of these disparate outcomes, we compared the gene expression profiles of the draining lymph node cells (LNC) of these two rat strains early (day 7) following a potentially arthritogenic challenge. LNC were tested both ex vivo and after restimulation with the disease-related antigen, mycobacterial heat-shock protein 65. Biotin-labeled fragment cRNA was generated from RNA of LNC and then hybridized with an oligonucleotide-based DNA microarray chip. The differentially expressed genes (DEG) were compared by limiting the false discovery rate to <5% and fold change ≥2.0, and their association with quantitative trait loci (QTL) was analyzed. This analysis revealed overall a more active immune response in WKY than LEW rats. Important differences were observed in the association of DEG with QTL in LEW vs. WKY rats. Both the number of upregulated DEG associated with rat arthritis-QTL and their level of expression were relatively higher in LEW when compared to WKY rat; however, the number of downregulated DEG-associated with rat arthritis-QTL as well as AIA-QTL were found to be higher in WKY than in LEW rats. In conclusion, distinct gene expression profiles define arthritis-susceptible versus resistant phenotype of MHC-compatible inbred rats. These results would advance our understanding of the pathogenesis of autoimmune arthritis and might also offer potential novel targets for therapeutic purposes.

M. paratuberculosis Heat Shock Protein 65 and Human Diseases: Bridging Infection and Autoimmunity

Mycobacterium avium subspecies paratuberculosis (MAP) is the known infectious cause of Johne's disease, an enteric inflammatory disease mostly studied in ruminant animals. MAP has also been implicated in the very similar Crohn's disease of humans as well as sarcoidosis. Recently, MAP has been associated with juvenile sarcoidosis (Blau syndrome), autoimmune diabetes, autoimmune thyroiditis, and multiple sclerosis. While it is intuitive to implicate MAP in granulomatous diseases where the microbe participates in the granuloma, it is more difficult to assign a role for MAP in diseases where autoantibodies are a primary feature. MAP may trigger autoimmune antibodies via its heat shock proteins. Mycobacterial heat shock protein 65 (HSP65) is an immunodominant protein that shares sequential and conformational elements with several human host proteins. This molecular mimicry is the proposed etiopathology by which MAP stimulates autoantibodies associated with autoimmune (type 1) diabetes, autoimmune (Hashimoto's) thyroiditis, and multiple sclerosis. This paper proposes that MAP is a source of mycobacterial HSP65 and acts as a trigger of autoimmune disease.

Microarray-based gene expression profiling reveals the mediators and pathways involved in the anti-arthritic activity of Celastrus-derived Celastrol

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints. The prolonged use of non-steroidal anti-inflammatory drugs and other newer drugs is associated with severe adverse reactions. Therefore, there is a need for newer anti-arthritic agents. Celastrol, a bioactive component of the Chinese herb Celastrus, possesses anti-arthritic activity as tested in the adjuvant arthritis (AA) model of rheumatoid arthritis (RA). However, the mechanism of action of Celastrol has not been fully defined. We reasoned that microarray analysis of the lymphoid cells of Celastrol-treated arthritic animals might provide vital clues in this regard. We isolated total RNA of the draining lymph node cells (LNCs) of Celastrol-treated (Tc) and vehicle-treated (Tp) arthritic Lewis rats that were restimulated in vitro with the disease-related antigen, mycobacterial heat-shock protein 65 (Bhsp65), and tested it using microarray gene chips. Also tested was RNA from LNCs of control arthritic rats just before any treatment (T₀). Seventy six genes involved in various biological functions were differentially regulated by Bhsp65 in LNCs of Tp group, and 19 genes among them were shared by the Tc group. Furthermore, a group of 14 genes was unique to Tc. When Tc and Tp were compared, many of the Bhsp65-induced genes were related to the immune cells, cellular proliferation and inflammatory responses. Our results revealed 10 differentially expressed genes and 14 pathways that constituted the "Celastrol Signature". Our results would help identify novel targets for RA therapy.

Celastrus treatment modulates antigen-induced gene expression in lymphoid cells of arthritic rats

Rheumatoid arthritis (RA) is a debilitating autoimmune disease of global prevalence and the disease process primarily targets the synovial joints. Despite improvements in the treatment of RA over the past decade, there still is a need for new therapeutic agents that are efficacious, less expensive, and free of severe adverse reactions. Celastrus has been used in China for centuries for the treatment of rheumatic diseases. Furthermore, we previously reported that ethanol extract of Celastrus aculeatus Merr. (Celastrus) attenuates adjuvant-induced arthritis (AA) in rats. However, the mechanisms underlying the anti-arthritic activity of Celastrus have not yet been fully defined. We reasoned that microarray analysis might offer useful insights into the pathways and molecules targeted by Celastrus. We compared the gene expression profiles of the draining lymph node cells (LNC) of Celastrus-treated (Tc) versus water-treated (Tw) rats, and each group with untreated arthritic rats (T(0)). LNC were restimulated with mycobacterial heat shock protein-65 (Bhsp65). We identified 104 differentially expressed genes (DEG) (8 upregulated, 96 downregulated) when comparing Tc with T(0) rats, in contrast to 28 (12 upregulated, 16 downregulated) when comparing Tw and T(0) rats. Further, 20 genes (6 upregulated, 14 downregulated) were shared by both Tw and Tc groups. Thus, Celastrus treatment (Tc) significantly downregulated a large proportion of genes compared to controls (Tw). The DEG were mainly associated with the processes of immune response, cell proliferation and apoptosis, and cell signaling. These results provide novel insights into the mechanism of Celastrus anti-arthritic activity, and unravel potential therapeutic targets for arthritis.

Suppression of autoimmune arthritis by Celastrus-derived Celastrol through modulation of pro-inflammatory chemokines

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the synovial joints, deformities, and disability. The prolonged use of conventional anti-inflammatory drugs is associated with severe adverse effects. Therefore, there is an urgent need for safer and less expensive therapeutic products. Celastrol is a bioactive component of Celastrus, a traditional Chinese medicine, and it possesses anti-arthritic activity. However, the mechanism of action of Celastrol remains to be fully defined. In this study based on the rat adjuvant-induced arthritis (AA) model of RA, we examined the effect of Celastrol on two of the key mediators of arthritic inflammation, namely chemokines and their receptors, and related pro-inflammatory cytokines. We treated arthritic Lewis rats with Celastrol (200μg/rat) or its vehicle by daily intraperitoneal (ip) injection beginning at the onset of AA. At the peak phase of AA, the sera, the draining lymph node cells, spleen adherent cells, and synovial-infiltrating cells of these rats were harvested and tested. Celastrol-treated rats showed a significant reduction in the levels of chemokines (RANTES, MCP-1, MIP-1α, and GRO/KC) as well as cytokines (TNF-α and IL-1β) that induce them, compared to the vehicle-treated rats. However, Celastrol did not have much effect on cellular expression of chemokine receptors except for an increase in CCR1. Further, Celastrol inhibited the migration of spleen adherent cells in vitro. Thus, Celastrol-induced suppression of various chemokines that mediate cellular infiltration into the joints might contribute to its anti-arthritic activity. Our results suggest that Celastrol might offer a promising alternative/adjunct treatment for RA.

A case of mistaken identity: HSPs are no DAMPs but DAMPERs

Until recently, the immune system was seen solely as a defense system with its primary task being the elimination of unwanted microbial invaders. Currently, however, the functional significance of the immune system has obtained a much wider perspective, to include among others the maintenance and restoration of homeostasis following tissue damage. In this latter aspect, there is a growing interest in the identification of molecules involved, such as the so-called danger or damage-associated molecular patterns (DAMPs), also called alarmins. Since heat shock proteins are archetypical molecules produced under stressful conditions, such as tissue damage or inflammation, they are frequently mentioned as prime examples of DAMPs (Bianchi, J Leukoc Biol 81:1-5, 2007; Kono and Rock, Nat Rev Immunol 8:279-289, 2008; Martin-Murphy et al., Toxicol Lett 192:387-394, 2010). See for instance also a recent review (Chen and Nunez, Science 298:1395-1401, 2010). Contrary to this description, we recently presented some of the arguments against a role of heat shock protein as DAMPs (Broere et al., Nat Rev Immunol 11:565-c1, 2011). With this perspective and reflection article, we hope to elaborate on this debate and provide additional thoughts to further ignite this discussion on this critical and evolving issue.

Sercarzian immunology--In memoriam. Eli E. Sercarz, 1934-2009

During his long career as a principal investigator and educator, Eli Sercarz trained over 100 scientists. He is best known for developing hen egg white lysozyme (HEL) as a model antigen for immunologic studies. Working in his model system Eli furthered our understanding of antigen processing and immunologic tolerance. His work established important concepts of how the immune system recognizes antigenic determinants processed from whole protein antigens; specifically he developed the concepts of immunodominance and crypticity. Later in his career he focused more on autoimmunity using a variety of established animal models to develop theories on how T cells can circumvent tolerance induction and how an autoreactive immune response can evolve over time. His theory of "determinant spreading" is one of the cornerstones of our modern understanding of autoimmunity. This review covers Eli's entire scientific career outlining his many seminal discoveries.

A cytokine-centric view of the pathogenesis and treatment of autoimmune arthritis

Cytokines are immune mediators that play an important role in the pathogenesis of rheumatoid arthritis (RA), an autoimmune disease that targets the synovial joints. The cytokine environment in the peripheral lymphoid tissues and the target organ (the joint) has a strong influence on the outcome of the initial events that trigger autoimmune inflammation. In susceptible individuals, these events drive inflammation and tissue damage in the joints. However, in resistant individuals, the inflammatory events are controlled effectively with minimal or no overt signs of arthritis. Animal models of human RA have permitted comprehensive investigations into the role of cytokines in the initiation, progression, and recovery phases of autoimmune arthritis. The discovery of interleukin-17 (IL-17) and its association with inflammation and autoimmune pathology has reshaped our viewpoint regarding the pathogenesis of arthritis, which previously was based on a simplistic T helper 1 (Th1)-Th2 paradigm. This review discusses the role of the newer cytokines, particularly those associated with the IL-17/IL-23 axis in arthritis. Also presented herein is the emerging information on IL-32, IL-33, and IL-35. Ongoing studies examining the role of the newer cytokines in the disease process would improve understanding of RA as well as the development of novel cytokine inhibitors that might be more efficacious than the currently available options.

Evidence of a role for Th17 cells in the breach of immune tolerance in arthritis

Th17 cells are thought to play a pathogenic role in various autoimmune diseases. Cytokines secreted by Th17 cells like IL-17, IL-17F and IL-22 have the capacity to mediate a massive inflammatory response. These proinflammatroy cytokines are likely to mediate the pathogenic potential of Th17 cells. Recent evidence suggests a role for Th17 cells in the breach of immune tolerance. This might shed some new light on the pathogenic role of Th17 cells in autoimmunity.

The gene expression profile of preclinical autoimmune arthritis and its modulation by a tolerogenic disease-protective antigenic challenge

Introduction

Autoimmune inflammation is a characteristic feature of rheumatoid arthritis (RA) and other autoimmune diseases. In the natural course of human autoimmune diseases, it is rather difficult to pinpoint the precise timing of the initial event that triggers the cascade of pathogenic events that later culminate into clinically overt disease. Therefore, it is a challenge to examine the early preclinical events in these disorders. Animal models are an invaluable resource in this regard. Furthermore, considering the complex nature of the pathogenic immune events in arthritis, microarray analysis offers a versatile tool to define the dynamic patterns of gene expression during the disease course.

Methods

In this study, we defined the profiles of gene expression at different phases of adjuvant arthritis (AA) in Lewis rats and compared them with those of antigen mycobacterial heat shock protein 65 (Bhsp65)-tolerized syngeneic rats. Purified total RNA (100 ng) extracted from the draining lymph node cells was used to generate biotin-labeled fragment cRNA, which was then hybridized with an oligonucleotide-based DNA microarray chip. Significance analysis of microarrays was used to compare gene expression levels between the two different groups by limiting the false discovery rate to < 5%. Some of the data were further analyzed using a fold change ≥2.0 as the cutoff. The gene expression of select genes was validated by quantitative real-time PCR.

Results

Intriguingly, the most dramatic changes in gene expression in the draining lymphoid tissue ex vivo were observed at the preclinical (incubation) phase of the disease. The affected genes represented many of the known proteins that participate in the cellular immune response. Interestingly, the preclinical gene expression profile was significantly altered by a disease-modulating, antigen-based tolerogenic regimen. The changes mostly included upregulation of several genes, suggesting that immune tolerance suppressed disease by activating disease-regulating pathways. We identified a molecular signature comprising at least 12 arthritis-related genes altered by Bhsp65-induced tolerance.

Conclusions

This is the first report of microarray analysis in the rat AA model. The results of this study not only advance our understanding of the early phase events in autoimmune arthritis but also help in identifying potential targets for the immunomodulation of RA.

Mycobacterium paratuberculosis and autism: is this a trigger?

Autism is a heterogeneous group of life-long neurologic problems that begin in childhood. Success in efforts to understand and treat autism has been mostly elusive. The role of autoimmunity in autism has gained recognition both for associated systemic autoimmune disease and the presence of brain autoantibodies in autistic children and their family members. There is an acknowledged genetic susceptibility to autism--most notably allotypes of complement C4. C4 defects are associated with several autoimmune diseases and also confer susceptibility to mycobacterial infections. Mycobacterium avium ss. paratuberculosis (MAP) causes an enteric inflammatory disease in ruminant animals (Johne's disease) and is the putative cause of the very similar Crohn's disease in humans. Humans are widely exposed to MAP in food and water. MAP has been also linked to ulcerative colitis, irritable bowel syndrome, sarcoidosis, Blau syndrome, autoimmune (Type 1) diabetes, Hashimoto's thyroiditis and multiple sclerosis. Environmental agents are thought to trigger autism in the genetically at risk. Molecular mimicry is the proposed mechanism by which MAP is thought to trigger autoantibodies. Autoantibodies to brain myelin basic protein (MBP) is a common feature of autism. This article considers the subset of autoimmunity-related autism patients and postulates that MAP, through molecular mimicry to its heat shock protein HSP65, triggers autism by stimulating antibodies that cross react with myelin basic protein (MBP).

Topical dermal application of essential oils attenuates the severity of adjuvant arthritis in Lewis rats

This study was aimed at examining the effect of an ointment containing essential oils (EO) on the severity of adjuvant arthritis (AA), an experimental model of human rheumatoid arthritis (RA), in Lewis rats and to define the underlying mechanisms. At the onset of AA, the rats received topical application twice daily of an ointment containing 20% EO or placebo ointment. The synovial fluid (SF) and synovium-infiltrating cells (SIC) of rats were tested for pro-inflammatory cytokines TNF-α and IL-1β. The hind paws and skin were examined histologically. The activity/level of matrix metalloproteinases (MMPs) and anti-mycobacterial heat-shock protein 65 (Bhsp65) antibodies were tested. Arthritic rats treated with ointment containing EO developed less severe clinical arthritis compared with the controls, and this activity was attributable to EO and not to the carrier oil. The levels of TNF-α and IL-1β, and the activity of MMPs in SF and SIC-lysate were significantly reduced in EO-treated arthritic rats compared with the controls. However, the levels of anti-Bhsp65 antibodies were unaffected by treatment. Thus, topical dermal delivery of EO-containing ointment down-modulates the severity of AA in Lewis rats by inhibiting defined mediators of inflammation. Such ointments should be tested in patients with RA and other arthritic conditions.

Celastrus-derived celastrol suppresses autoimmune arthritis by modulating antigen-induced cellular and humoral effector responses

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation and articular damage. Proinflammatory cytokines, antibodies, and matrix-degrading enzymes orchestrate the pathogenic events in autoimmune arthritis. Accordingly, these mediators of inflammation are the targets of several anti-arthritic drugs. However, the prolonged use of such drugs is associated with severe adverse reactions. This limitation has necessitated the search for less toxic natural plant products that possess anti-arthritic activity. Furthermore, it is imperative that the mechanism of action of such products be explored before they can be recommended for further preclinical testing. Using the rat adjuvant-induced arthritis model of human RA, we demonstrate that celastrol derived from Celastrus has potent anti-arthritic activity. This suppression of arthritis is mediated via modulation of the key proinflammatory cytokines (IL-17, IL-6, and IFN-γ) in response to the disease-related antigens, of the IL-6/IL-17-related transcription factor STAT3, of antibodies directed against cyclic citrullinated peptides and Bhsp65, and of the activity of matrix metalloproteinase-9 and phospho-ERK. Most of the clinical and mechanistic attributes of celastrol are similar to those of Celastrus extract. Several studies have addressed the antitumor activity of celastrol. Our study highlights the anti-arthritic activity of Celastrus-derived celastrol and the underlying mechanisms. These results provide a strong rationale for further testing and validation of the use of celastrol and the natural plant extract from Celastrus as an adjunct (with conventional drugs) or alternative modality for the treatment of RA.

Heat-killed Trypanosoma cruzi induces acute cardiac damage and polyantigenic autoimmunity

Chagas heart disease, caused by the protozoan parasite Trypanosoma cruzi, is a potentially fatal cardiomyopathy often associated with cardiac autoimmunity. T. cruzi infection induces the development of autoimmunity to a number of antigens via molecular mimicry and other mechanisms, but the genesis and pathogenic potential of this autoimmune response has not been fully elucidated. To determine whether exposure to T. cruzi antigens alone in the absence of active infection is sufficient to induce autoimmunity, we immunized A/J mice with heat-killed T. cruzi (HKTC) emulsified in complete Freund's adjuvant, and compared the resulting immune response to that induced by infection with live T. cruzi. We found that HKTC immunization is capable of inducing acute cardiac damage, as evidenced by elevated serum cardiac troponin I, and that this damage is associated with the generation of polyantigenic humoral and cell-mediated autoimmunity with similar antigen specificity to that induced by infection with T. cruzi. However, while significant and preferential production of Th1 and Th17-associated cytokines, accompanied by myocarditis, develops in T. cruzi-infected mice, HKTC-immunized mice produce lower levels of these cytokines, do not develop Th1-skewed immunity, and lack tissue inflammation. These results demonstrate that exposure to parasite antigen alone is sufficient to induce autoimmunity and cardiac damage, yet additional immune factors, including a dominant Th1/Th17 immune response, are likely required to induce cardiac inflammation.

Immunomodulation of Autoimmune Arthritis by Herbal CAM

Rheumatoid arthritis (RA) is a debilitating autoimmune disease of global prevalence. The disease is characterized by synovial inflammation leading to cartilage and bone damage. Most of the conventional drugs used for the treatment of RA have severe adverse reactions and are quite expensive. Over the years, increasing proportion of patients with RA and other immune disorders are resorting to complementary and alternative medicine (CAM) for their health needs. Natural plant products comprise one of the most popular CAM for inflammatory and immune disorders. These herbal CAM belong to diverse traditional systems of medicine, including traditional Chinese medicine, Kampo, and Ayurvedic medicine. In this paper, we have outlined the major immunological pathways involved in the induction and regulation of autoimmune arthritis and described various herbal CAM that can effectively modulate these immune pathways. Most of the information about the mechanisms of action of herbal products in the experimental models of RA is relevant to arthritis patients as well. The study of immunological pathways coupled with the emerging application of genomics and proteomics in CAM research is likely to provide novel insights into the mechanisms of action of different CAM modalities.

The HSP60 immune system network

Heat shock proteins (HSPs) were initially discovered as participants in the cellular response to stress. It is now clear, however, that self and microbial HSPs also play an important role in the control of the immune response. Here, we focus on HSP60 and its interactions with both the innate and adaptive immune system in mammals. We also consider that circulating HSP60 and the quantities and specificities of serum antibodies to HSP60 provide a biomarker to monitor the immune status of the individual. Thus, the dual role of HSP60 as an immune modulator and a biomarker, provides an opportunity to modulate immunity for therapeutic purposes, and to monitor the immune response in health and disease.

Interleukin-27 and interferon-gamma are involved in regulation of autoimmune arthritis

Inflammation underlying immune pathology and tissue damage involves an intricate interplay between multiple immunological and biochemical mediators. Cytokines represent the key immune mediators that trigger a cascade of reactions that drive processes such as angiogenesis and proteolytic damage to tissues. IL-17 has now been shown to be a pivotal cytokine in many autoimmune diseases, supplanting the traditional Th1-Th2 paradigm. Also, the dual role of proinflammatory IFN-γ has unraveled new complexities in the cytokine biology of such disorders. A major hurdle in fully understanding the effector pathways in these disorders is the lack of information regarding the temporal kinetics of the cytokines during the course of the disease, as well as the interplay among the key cytokines. Using an experimental model of arthritic inflammation, we demonstrate that the temporal expression of cytokines during the incubation phase is a critical determinant of disease susceptibility. The susceptible rats raised a vigorous IL-17 response early, followed by IFN-γ and IL-27 response in that sequence, whereas the resistant rats displayed an early and concurrent response to these three cytokines. Accordingly, treatment with exogenous IFN-γ/IL-27 successfully controlled arthritic inflammation and inhibited the defined mediators of inflammation, angiogenesis, cell survival, apoptosis, and tissue damage. Furthermore, IFN-γ enhanced IL-27 secretion, revealing a cooperative interplay between the two cytokines. Our results offer a novel immunobiochemical perspective on the pathogenesis of autoimmune arthritis and its therapeutic control.

Suppression of ongoing experimental arthritis by a chinese herbal formula (huo-luo-xiao-ling dan) involves changes in antigen-induced immunological and biochemical mediators of inflammation

Rheumatoid arthritis (RA) is one of the major autoimmune diseases of global prevalence. The use of the anti-inflammatory drugs for the treatment of RA is associated with severe adverse reactions and toxicity. This limitation has necessitated the search for novel therapeutic products. We report here a traditional Chinese medicine-based herbal formula, Huo luo xiao ling dan (HLXL), which has potent antiarthritic activity as validated in the rat adjuvant-induced arthritis (AA) model. HLXL (2.3 g/Kg) was fed to Lewis (RT.1(1)) rats daily by gavage beginning at the onset of arthritis and then continued through the observation period. HLXL inhibited the severity of ongoing AA. This suppression of arthritis was associated with significant alterations in the T cell proliferative and cytokine responses as well as the antibody response against the disease-related antigen, mycobacterial heat-shock protein 65 (Bhsp65). There was a reduction in the level of the proinflammatory cytokines IL-17 and IL-1β but enhancement of the anti-inflammatory cytokine IL-10 level. In addition, there was inhibition of both the anti-Bhsp65 antibody response and the serum level of nitric oxide. Thus, HLXL is a promising CAM modality for further testing in RA patients.

The involvement of heat-shock proteins in the pathogenesis of autoimmune arthritis: a critical appraisal

OBJECTIVES

To review the literature on the role of heat-shock proteins (HSPs) in the pathogenesis of autoimmune arthritis in animal models and patients with rheumatoid arthritis (RA).

METHODS

The published literature in Medline (PubMed), including our published work on the cell-mediated as well as humoral immune response to various HSPs, was reviewed. Studies in the preclinical animal models of arthritis as well as RA were examined critically and the data are presented.

RESULTS

In experimental arthritis, disease induction by different arthritogenic stimuli, including an adjuvant, led to immune response to mycobacterial HSP65 (BHSP65). However, attempts to induce arthritis by a purified HSP have not met with success. There are several reports of a significant immune response to HSP65 in RA patients. However, the issue of cause and effect is difficult to address. Nevertheless, several studies in animal models and a couple of clinical trials in RA patients have shown the beneficial effect of HSPs against autoimmune arthritis.

CONCLUSIONS

There is a clear association between immune response to HSPs, particularly HSP65, and the initiation and propagation of autoimmune arthritis in experimental models. The correlation is relatively less convincing in RA patients. In both cases, the ability of HSPs to modulate arthritis offers support, albeit an indirect one, for the involvement of these antigens in the disease process.

Self heat-shock protein 65-mediated regulation of autoimmune arthritis

Heat-shock proteins (Hsps) have been invoked in the pathogenesis of a variety of autoimmune diseases. The mycobacterial heat-shock protein 65 (Bhsp65) has been studied extensively as one of the antigenic triggers of autoimmunity in experimental models of, as well as patients with, rheumatoid arthritis. As Hsps are highly conserved and immunogenic, it is generally anticipated that self Hsps might serve as the endogenous targets of the immune response initiated by the homologous foreign Hsps. Contrary to this expectation, studies in the rat adjuvant arthritis (AA) model have revealed that priming of the self (rat) hsp65 (Rhsp65)-directed T cells in the Lewis rat leads to protection against AA instead of disease induction or aggravation. The arthritis-protective attribute of the self hsp65 is also evident following spontaneous priming of the anti-Rhsp65 T cells during the natural course of AA. Furthermore, immunization of rats with human hsp60, or with Bhsp65 peptides that are crossreactive with the corresponding self hsp65 peptides, leads to protection against AA. Importantly, high levels of T cell reactivity against self hsp60 in patients with juvenile idiopathic arthritis positively correlate with a favorable outcome of the disease. Thus, immune response against self hsp65 in autoimmune arthritis is protective rather than being pathogenic.

The determinants of susceptibility/resistance to adjuvant arthritis in rats

Adjuvant arthritis (AA) serves as an excellent model for human rheumatoid arthritis. AA is readily inducible in certain rat strains, but not in others. Susceptibility/resistance to AA is determined by multiple factors. Among the genetic factors, both MHC and non-MHC genes contribute to arthritis susceptibility, and specific quantitative trait loci show association with the severity of the disease. Differential T-cell proliferative and cytokine responses, as well as antibody responses, to heat-shock proteins are evident when comparing AA-susceptible and AA-resistant rats. In addition, neuroendocrine factors and the housing environment can further modulate arthritis susceptibility/severity in particular rat strains.

Tolerization with Hsp65 induces protection against adjuvant-induced arthritis by modulating the antigen-directed interferon-gamma, interleukin-17, and antibody responses

OBJECTIVE

Pretreatment of Lewis rats with soluble mycobacterial Hsp65 affords protection against subsequent adjuvant-induced arthritis (AIA). This study was aimed at unraveling the mechanisms underlying mycobacterial Hsp65-induced protection against arthritis, using contemporary parameters of immunity.

METHODS

Lewis rats were given 3 intraperitoneal injections of mycobacterial Hsp65 in solution prior to the initiation of AIA with heat-killed Mycobacterium tuberculosis. Thereafter, mycobacterial Hsp65-specific T cell proliferative, cytokine, and antibody responses were tested in tolerized rats. The roles of anergy and the indoleamine 2,3 dioxygenase (IDO)-tryptophan pathway in tolerance induction were assessed, and the frequency and suppressive function of CD4+FoxP3+ Treg cells were monitored. Also tested was the effect of mycobacterial Hsp65 tolerization on T cell responses to AIA-related mycobacterial Hsp70, mycobacterial Hsp10, and rat Hsp65.

RESULTS

The AIA-protective effect of mycobacterial Hsp65-induced tolerance was associated with a significantly reduced T cell proliferative response to mycobacterial Hsp65, which was reversed by interleukin-2 (IL-2), indicating anergy induction. The production of interferon-gamma (but not IL-4/IL-10) was increased, with concurrent down-regulation of IL-17 expression by mycobacterial Hsp65-primed T cells. Neither the frequency nor the suppressive activity of CD4+FoxP3+ T cells changed following tolerization, but the serum level of anti-mycobacterial Hsp65 antibodies was increased. However, no evidence was observed for a role of IDO or cross-tolerance to mycobacterial Hsp70, mycobacterial Hsp10, or rat Hsp65.

CONCLUSION

Tolerization with soluble mycobacterial Hsp65 leads to suppression of IL-17, anergy induction, and enhanced production of anti-mycobacterial Hsp65 antibodies, which play a role in protection against AIA. These results are relevant to the development of effective immunotherapeutic approaches for autoimmune arthritis.